No date on the Jewish calendar corresponds to a specific date on the Gregorian calendar. Nisan 16 this year corresponds to April 24. Nisan 16 last year was April 7. Nisan 16 the year before that was April 17.
The reason for this is because the calendars work differently. The Gregorian calendar is a solar calendar. It has a straight 365 days, to match the (roughly) 365.25 years in each solar year, and you have leap years every 4 years to make up for the quarter of the day. The Hebrew calendar, however, is a lunisolar calendar. Its months are all 29 or 30 days (it takes about 29.5 days for the new moon to become full and then return to being new, and so by having months of that length it will make it so you have a new moon around the start of each month). But this leaves you about 10 days short of the full 365.25 days in a solar year. A pure lunar calendar like the Islamic calendar therefore has its months never associated with any particular season (e.g. Ramadan cycles throughout the various seasons; it's in March this year, but was in April in 2020, June in 2015, August in 2010, October in 2005, and November in 2000). A lunisolar calendar like the Hebrew calendar solves the issue by having an extra month in some years. Just like how a leap year in the Gregorian calendar adds a day to balance things out, a lunisolar calendar adds a month to make sure the months stay in the same rough seasons of the year.
However, since the calendars are operating on fundamentally different principles (solar vs. lunisolar), there is never any particular date on one of the calendars that will every year correspond (or nearly correspond) to the same date on the other calendar.