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          532        200 
1992          936        367 
1993         1672        611 
1994         2339        844 
1995         4430       1529 
1996         3605       1266 
1997         2337        797 
1998        23345       9841 
1999        14644       5620 
2000        40807      16947 
2001        41911      16355 
2002        33126      14786 
2003        62243      25800 
2004        48880      18759 
2005        87479      26854 
2006       113333      36152 
2007       208383      63762 
2008       129549      36803 
2009       105206      29535 
2010       122314      33918 
2011       184397      50968 
2012       170903      47273 
2013       266827      75656 
2014       664945     169562 
2015       777430     205986 
2016       575044     153948 
2017       560261     153377 
2018       407461     114333 
2019       924945     225875 
2020       716296     183890 
2021      1002679     230448 
2022       691376     197769 
2023       637302     183370 
2024        27920       8144