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          512        193 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         4146       1432 
1996         3581       1258 
1997         2331        795 
1998        23296       9821 
1999        14569       5588 
2000        40583      16846 
2001        41584      16215 
2002        32673      14606 
2003        61612      25534 
2004        48369      18555 
2005        86214      26494 
2006       111712      35675 
2007       205914      63088 
2008       126873      36083 
2009       103334      29025 
2010       119906      33277 
2011       180212      49830 
2012       167368      46309 
2013       259409      73643 
2014       645270     164567 
2015       749407     198893 
2016       575914     153726 
2017       611879     163765 
2018       406322     113861 
2019       930300     226886 
2020       697216     179005 
2021       906024     217251 
2022       676337     193477 
2023       614281     176827 
2024       156224      44743