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          444        170 
1992          721        293 
1993         1283        478 
1994         1631        600 
1995         2903       1015 
1996         2895       1024 
1997         1787        619 
1998        21454       9129 
1999        12875       4962 
2000        38003      15695 
2001        39351      15255 
2002        32772      14410 
2003        56325      23479 
2004        45369      17433 
2005        79961      24640 
2006       102921      33099 
2007       187727      58195 
2008       106508      30604 
2009        89449      25258 
2010       141560      38072 
2011       150855      41895 
2012       141883      39364 
2013       215097      61339 
2014       547487     139372 
2015       795291     209282 
2016       645767     167674 
2017       544539     147389 
2018       338666      95222 
2019       851442     207866 
2020       593401     150559 
2021       803830     190221 
2022       608559     174210 
2023       548505     156971 
2024       607717     174399 
2025       524545     149953