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          767        309 
1993         1356        504 
1994         1749        641 
1995         3303       1149 
1996         3321       1168 
1997         2291        783 
1998        23113       9750 
1999        14432       5532 
2000        40015      16593 
2001        40857      15917 
2002        32078      14336 
2003        59937      24891 
2004        47350      18168 
2005        83215      25602 
2006       107366      34399 
2007       197191      60734 
2008       118733      33875 
2009        97683      27496 
2010       112481      31330 
2011       166648      46160 
2012       157256      43543 
2013       233012      66309 
2014       576658     147085 
2015       755856     197703 
2016       671897     173963 
2017       573080     154798 
2018       370107     103856 
2019       894159     218516 
2020       645839     164676 
2021       865280     206228 
2022       641376     183628 
2023       586411     167717 
2024       515873     149052