Bernie Sanders and his wife made more than $1 million in both 2016 and 2017, newly released tax returns have revealed, shining a light on the wealth of the Left-wing presidential hopeful. Mr Sanders, a self-proclaimed democratic socialist who sits as an independent in the US Senate, enjoyed the surge of income in part thanks to books he has written about politics. The 77-year-old released 10 years of tax returns on Monday, following similar moves by rivals who are also seeking the Democratic Party's 2020 presidential nomination. The revelation is politically challenging for Mr Sanders given he has railed against the 'millionaires and billionaires' and their influence over the political system. Mr Sanders said in a statement: 'These tax returns show that our family has been fortunate. I am very grateful for that, as I grew up in a family that lived paycheck to paycheck and I know the stress of economic insecurity.' The 2018 tax return, the most recent released, showed Mr Sanders and his wife Jane O'Meara Sanders receiving an income of $561,293. That puts the Sanders in the top 1 per cent of US earners, according to the Economic Policy Institute, which said families receiving more than around $422,000 a year were in that bracket. About $393,000 of the Sanders's 2018 earnings came from book income. The pair reported giving $19,000 to charity ' though other charitable gifts may have gone undeclared. The pair paid an effective tax rate of 26 per cent in 2018, according to the Sanders campaign. Mr Sanders said in his statement: "I consider paying more in taxes as my income rose to be both an obligation and an investment in our country. "I will continue to fight to make our tax system more progressive so that our country has the resources to guarantee the American Dream to all people.' Bernie Sanders ran Hillary Clinton close in the 2016 Democratic presidential nomination race, but ultimately fell short Credit: REUTERS/Brian Snyder Mr Sanders, a Vermont senator, sprung to worldwide prominence when he ran a closer than expected race against Hillary Clinton for the Democrats' 2016 presidential nomination. He ended up losing to Mrs Clinton but his unashamed left-wing policy pitch inspired scores of young Americans and drew comparisons to Jeremy Corbyn, the Labour leader. Shortly after the 2016 election, Mr Sanders'book Our Revolution: A Future To Believe In was published. It was eventually translated into five languages. A young-adult book called Bernie Sanders' Guide to Political Revolution was published the following year and another, titled Where We Go From Here, came out last year. Given Mr Sanders' left-wing policy program ' free government-funded healthcare for all, a $15 minimum wage, no tuition fees ' he has been challenged to square his new-found wealth with his political stance. 'I wrote a best-selling book,' Mr Sanders said in an interview with The New York Times last week. 'If you write a best-selling book, you can be a millionaire, too.' During a town hall debate run by Fox News on Monday, Mr Sanders acknowledged he had increased his income by publishing a book and declined to apologise. 'I guess the president watches your network a little bit, right'" Mr Sanders said to the moderators. "Hey, President Trump. My wife and I just released 10 years. Please do the same." Mr Sanders had held up publishing his full tax returns during his 2016 bid for the White House, releasing just his 2014 return. Leading rivals for the 2020 nomination have released years of tax returns. Elizabeth Warren, the Massachusetts senator, has released 10 years' worth and Kamala Harris, the California senator, has released 15 years of returns. Mr Trump is yet to release any of his tax returns, despite promising to do so during the 2016 presidential campaign once an audit was complete. Committees in the House of Representatives which are controlled by the Democrats are attempting to force their release with subpoenas. The White House is fighting the move. Click here to read full news..