The police estimate for yesterday's tax day tea party is 500. Last year, the tea party claimed to have had 10,000 at their rally in Kiener Plaza. However, since the maximum attendance of Kiener Plaza is only 3,000 (h/t FiredUp), we'll be generous and say that attendence this year was 500/3000 or 1/6 of the attendance from last year.
Or, we could go by the Tea Party's own manufactured numbers. They're claiming four times as many people as the police estimates showed up, or around 2,000. 2,000 divided by 10,000 = 1/5
However you look at it, the tea party is losing steam.