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          512        193 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         3943       1364 
1996         3581       1258 
1997         2331        795 
1998        23285       9817 
1999        14561       5585 
2000        40567      16838 
2001        41966      16342 
2002        32656      14599 
2003        61581      25521 
2004        48321      18535 
2005        86177      26482 
2006       111623      35648 
2007       205712      63032 
2008       126721      36042 
2009       103235      28997 
2010       119800      33248 
2011       179947      49758 
2012       167088      46236 
2013       259045      73543 
2014       644451     164366 
2015       748844     198742 
2016       575318     153551 
2017       613878     164227 
2018       406183     113826 
2019       934335     228008 
2020       696937     178941 
2021       942632     224964 
2022       674233     192873 
2023       613413     176574 
2024       161799      46137