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         1684        618 
1995         3081       1075 
1996         2980       1053 
1997         1866        644 
1998        21936       9303 
1999        13560       5202 
2000        38676      15989 
2001        39480      15337 
2002        35205      15276 
2003        57821      24059 
2004        46402      17803 
2005        81570      25109 
2006       105233      33772 
2007       192109      59370 
2008       112822      32295 
2009        93535      26358 
2010       133279      36264 
2011       158703      44014 
2012       149955      41548 
2013       222087      63269 
2014       565676     144112 
2015       798628     210115 
2016       659313     171280 
2017       554795     150207 
2018       352977      99163 
2019       866402     211497 
2020       619460     157690 
2021       834678     198220 
2022       623035     178331 
2023       560540     160328 
2024       621580     179059 
2025       206399      58983