An average of about 650 per year are reported, so multiply that by 5 and there's your answer.
Many in the past few years.
There is really no explaination.
five
17 animals have been etinct in the past 200 years
There have been so many sightings of UFOs that it is nearly impossible to calculate the exact number of UFO sightings, but there has been an increase in the sightings ever since the late nineties to early eighties. At that time technology and communication form was advancing, and the very popular and intriguing TV show called THE X-files aired.
From 1646 to 2011 there have been 88 leap years.
Thousands of reported sightings over hundreds of years. The Native Indians knew about Bigfoot long before European immigrants came to North America. Records have only been kept for the last hundred years or so, so an accurate count is not possible.
there's 500 volcanoes that have been active int he past 2000 years
There have been about 6,300 tornadoes in the U.S. in the past 5 years with more worldwide.
10
65
many improvement have been made over years