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         2081        755 
1995         3345       1163 
1996         3562       1251 
1997         2320        791 
1998        23173       9774 
1999        14481       5552 
2000        40149      16651 
2001        41809      16248 
2002        32156      14382 
2003        60401      25068 
2004        47572      18246 
2005        83902      25809 
2006       108604      34761 
2007       199721      61414 
2008       121254      34557 
2009        98989      27850 
2010       114584      31886 
2011       169961      47052 
2012       159560      44161 
2013       240071      68222 
2014       582763     149678 
2015       705258     187069 
2016       678004     176062 
2017       577554     156109 
2018       377899     105997 
2019       904748     221433 
2020       653954     166989 
2021       872252     207995 
2022       655265     187407 
2023       597164     170943 
2024       374753     108934