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          471        179 
1992          743        301 
1993         1308        487 
1994         1681        617 
1995         3069       1071 
1996         2980       1053 
1997         1863        643 
1998        21760       9244 
1999        13553       5195 
2000        38649      15978 
2001        39467      15331 
2002        32280      14299 
2003        57787      24045 
2004        46368      17790 
2005        81495      25086 
2006       105177      33756 
2007       191964      59330 
2008       112604      32238 
2009        93359      26310 
2010       141388      38167 
2011       158456      43948 
2012       149716      41480 
2013       221676      63152 
2014       565100     143966 
2015       798237     210062 
2016       659758     171459 
2017       555462     150368 
2018       352462      99018 
2019       865165     211183 
2020       618330     157380 
2021       832701     197774 
2022       621720     177959 
2023       559501     160029 
2024       618283     178123 
2025       206094      58893