Ransomware has received considerable news coverage in recent years, in part due to several attacks against high-profile corporate targets. Little is known, however, about the prevalence and characteristics of ransomware attacks on the general population, what proportion of users pay, or how users perceive risks and respond to attacks. Using a detailed survey of a representative sample of 1,180 American adults, we estimate that 2%-3% of respondents were affected over a 1-year period between 2016 and 2017. The average payment amount demanded was $530 and only a small fraction of affected users (about 4% of those affected) reported paying. Perhaps surprisingly, cryptocurrencies were typically only one of several payment options, suggesting that they may not be a primary driver of ransomware attacks. We conclude our analysis by developing a simple proof-of-concept method for risk-assessment based on self-reported security habits.