Major corporate takeovers have occurred at a blistering pace this year, with the latest on Monday the biggest of them all.

Major corporate takeovers have occurred at a blistering pace this year, with the latest on Monday the biggest of them all.

Drugmakers Pfizer and Allergan will join in a $160 billion deal.

No sector was hotter than health care, which saw unprecedented activity in mergers and acquisitions. Here's some numbers to put 2015 into perspective.

$1.99 trillion: The value of all mergers and acquisitions completed or pending so far this year across all sectors in the U.S.

1 in 5: The ratio of total dollars spent on health care companies.

245 percent: That's how much the combined value of all health care deals increased compared with just five years ago, well over three times the total value.

277: That's how many more M&A deals were pursued five years ago, showing how massive health care deals have become.

$451 billion: The total value of M&A in health care, which was greater than all M&A activity in the telecom and energy sectors combined.

Source: Dealogic