Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          503        190 
1992          936        367 
1993         1669        610 
1994         2326        839 
1995         3793       1314 
1996         3578       1257 
1997         2335        796 
1998        23274       9813 
1999        14542       5577 
2000        40514      16813 
2001        43115      16722 
2002        32584      14567 
2003        61392      25449 
2004        48116      18456 
2005        85790      26368 
2006       111208      35525 
2007       204994      62832 
2008       126063      35863 
2009       102603      28825 
2010       119150      33081 
2011       178895      49471 
2012       166034      45943 
2013       257146      72948 
2014       642777     163488 
2015       743844     197393 
2016       573030     152916 
2017       611265     163905 
2018       404237     113313 
2019       942001     230504 
2020       693681     177908 
2021       901038     215791 
2022       668880     191311 
2023       609605     175465 
2024       199915      57506