The percentages TC posted are pretty close to what I've concluded from many sources. Though there is disagreement on the numbers.
80 American Colonists in Parkers Company stood against Pitcairns force of 1500 in Lexington and strung out on the road; and the Colonists had approximately 4,000 roused in the countryside that night. Once the fighting started, and the Brits started their retreat they were hounded all the way back to Boston throughout the day of April 19th.
By the morning of April 20th, 15,000 Colonists from all over New England had put the British under siege.
It's clear by the results in the first 24hrs that there was widespread support for rebellion. The British were amazed at the logistics ability of the Colonists throughout the first days fighting. That logistical capability came from widespread local support.
Interesting to note. The Colonists had basically no political support in the Continental Congress for the first 3-6 months. In fact the Congress sent a boot licking Oops Letter to King George called the Olvie Branch petition
http://www.revolutionary-war-and-beyond ... -text.html