Silicon Valley’s relationship with Washington is becoming much cozier, at least as far as political contributions are concerned. Yet it can be hard to tell, because the tech industry is not eager to show it.

The industry has spent $71 million so far this year on lobbying, and last year spent $141 million, according to the Center for Responsive Politics. Yet the information technology industry ranks near the bottom of an annual list that attempts to grade large corporations on how well they voluntarily and publicly disclose their political activities.

At the most secretive end of the spectrum, two tech companies, Netflix and Salesforce.com, received a score of zero. At the most transparent end, three tech companies — Microsoft, Qualcomm and Intel — were ranked among the top five. Google, Amazon and Facebook all received below-average scores; Apple’s and Yahoo’s were slightly above average.

Tech companies’ average score this year was 44 percent, compared with an average 56.4 percent score for the 300 companies on the Index of Corporate Political Disclosure and Accountability, published Wednesday by the Center for Political Accountability and the Zicklin Center for Business Ethics Research at the University of Pennsylvania’s Wharton School of Business.