I’d guess this is a reliable source:

United Nations Regular Budget Contributions: Members Compared
January 22, 2010 - RL30605
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Starting January 1, 2001, the United States was assessed to pay 22% of the annual United Nations (U.N.) regular budget. For calendar year 2008, 22% of the U.N. regular budget amounted to $453,338,391. Prior to January 1, 2001, the assessment level for the United States was 25%. This report shows, for the years 1989 through 2008, the assessment level, actual payment, and total outstanding contributions for the United States and each of the other U.N. members assessed at 1% or higher. From 2004 to 2008, a new category is included: the countries with assessments at 0.5% or larger but less than 1%. Three of these countries had, at some time since 1989, been assessed at 1%. Aggregated figures are provided for the rest of the U.N. membership. In 2008, the United States and 16 other nations were assessed to pay 86.514% of the U.N. budget. Contributors in the middle category were collectively assessed to pay 6.220%. In 2008, of the top 17 assessed countries, the United States only failed to pay its entire assessment and maintained unpaid or outstanding contributions. The matter of U.S. funding to the United Nations has been a high-profile congressional issue for a number of years. …

opencrs.com

I’m not interested enough to download and read the entire document. If I stay up any later I’m going to finish my son’s caramel corn too. So, good night eveyrbody!