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         1998        727 
1995         3339       1161 
1996         3562       1251 
1997         2320        791 
1998        23173       9774 
1999        14481       5552 
2000        40142      16648 
2001        45347      17425 
2002        32134      14373 
2003        60371      25057 
2004        47560      18242 
2005        83848      25793 
2006       108501      34732 
2007       199598      61382 
2008       121079      34510 
2009        98903      27825 
2010       114432      31847 
2011       169649      46967 
2012       159425      44124 
2013       239575      68085 
2014       582092     149506 
2015       704584     186881 
2016       677961     176055 
2017       576812     155981 
2018       377839     105968 
2019       904226     221266 
2020       653407     166814 
2021       871834     207894 
2022       646461     185093 
2023       594963     170092 
2024       371714     108083