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         1752        642 
1995         3318       1154 
1996         3434       1207 
1997         2294        784 
1998        23133       9758 
1999        14451       5540 
2000        40071      16617 
2001        40928      15946 
2002        32703      14552 
2003        60102      24955 
2004        47452      18203 
2005        83463      25675 
2006       107807      34527 
2007       198041      60966 
2008       119483      34082 
2009        98201      27638 
2010       113238      31529 
2011       167827      46474 
2012       158032      43754 
2013       235457      66976 
2014       578967     148696 
2015       699904     185595 
2016       675022     175237 
2017       575823     155514 
2018       372884     104622 
2019       898276     219612 
2020       649576     165632 
2021       868112     206981 
2022       643433     184222 
2023       587062     168049 
2024       450355     131273