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          492        186 
1992          770        310 
1993         1356        504 
1994         1755        643 
1995         3321       1155 
1996         3544       1245 
1997         2300        785 
1998        23156       9767 
1999        14470       5548 
2000        40113      16635 
2001        40947      15958 
2002        32077      14349 
2003        60202      24992 
2004        47510      18224 
2005        83604      25719 
2006       107981      34579 
2007       198613      61118 
2008       120007      34224 
2009        98504      27718 
2010       113656      31640 
2011       168463      46644 
2012       158484      43870 
2013       236848      67360 
2014       580037     148979 
2015       701492     186022 
2016       676985     175699 
2017       576183     155710 
2018       374532     105070 
2019       900858     220308 
2020       651241     166116 
2021       869519     207318 
2022       644576     184544 
2023       592196     169441 
2024       428240     124745