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          444        170 
1992          721        293 
1993         1280        477 
1994         1628        599 
1995         2894       1012 
1996         2895       1024 
1997         1784        618 
1998        21448       9126 
1999        12857       4955 
2000        37945      15669 
2001        39081      15152 
2002        34853      15105 
2003        56762      23609 
2004        45219      17375 
2005        79772      24581 
2006       102685      33027 
2007       187053      58015 
2008       105557      30349 
2009        88703      25064 
2010       141009      37927 
2011       149540      41536 
2012       140362      38954 
2013       213950      61014 
2014       543499     138318 
2015       795844     209474 
2016       639249     165511 
2017       542350     146838 
2018       336289      94553 
2019       849480     207501 
2020       588719     149275 
2021       799386     189014 
2022       605856     173442 
2023       545904     156226 
2024       603446     173391 
2025       541902     154402