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         3428       1205 
1997         2294        784 
1998        23133       9758 
1999        14449       5539 
2000        40069      16616 
2001        40926      15945 
2002        32703      14552 
2003        60102      24955 
2004        47452      18203 
2005        83455      25673 
2006       107787      34522 
2007       198022      60961 
2008       119476      34080 
2009        98189      27635 
2010       113226      31527 
2011       167784      46463 
2012       158001      43745 
2013       235422      66966 
2014       578941     148689 
2015       699890     185590 
2016       674884     175203 
2017       575728     155488 
2018       372802     104598 
2019       898201     219592 
2020       649540     165622 
2021       868054     206966 
2022       643347     184196 
2023       587002     168033 
2024       450319     131263