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          468        178 
1992          740        300 
1993         1306        486 
1994         1672        614 
1995         3021       1055 
1996         2968       1049 
1997         1847        637 
1998        21635       9205 
1999        13318       5117 
2000        38568      15947 
2001        39369      15293 
2002        33233      14612 
2003        57692      24008 
2004        46239      17743 
2005        81256      25018 
2006       104853      33662 
2007       191553      59221 
2008       112044      32088 
2009        92836      26172 
2010       145191      39006 
2011       157468      43689 
2012       148821      41239 
2013       220609      62860 
2014       565129     144004 
2015       798366     210179 
2016       658345     171095 
2017       554587     150121 
2018       351136      98647 
2019       863066     210690 
2020       616398     156871 
2021       829236     196901 
2022       619310     177281 
2023       558355     159730 
2024       617120     177837 
2025       220419      62995