The FDA approved 46 new drugs in 2017, a more than two-fold increase from the year prior, according to Reuters.

Here are four things to know.

1. The figure marks a 21-year high for the agency, which has made greater efforts to streamline and simplify the drug approval process under FDA head Scott Gottlieb, MD.

2. Many of the new drugs were intended to treat rare diseases and types of cancers for very small patient populations.

3. The annual tally does not include Novartis, Gilead Sciences and Spark Therapeutics’ new cell and gene therapies, which were approved through a separate regulatory category.

4. Several medications slated for approval in the first quarter of 2018 actually got approved in 2017, which may slow the pace of drug approvals for this year.