many years. Over a last decade growing interest to this topic has been stimulated by technological advances allowing deeper insight into the structure of vortices as well as investigation of new exotic vortex states. In particular, local density of states (LDOS) measurements with the help of scanning tunneling spectroscopy techniques have been proven to be an effective tool of experimental study of electronic structure of Abrikosov vortices[@STSHess; @STSRoditchev; @STSmore1; @STSmore2; @RMP-2007]. The observation of the zero-bias anomaly of tunneling conductance at the center of each vortex in these experiments clearly confirmed the existence of bound vortex core states predicted by Caroli, de Gennes and Matricon (CdGM)[@CdGM]. The wave functions of the subgap states are localized inside the vortex core because of the Andreev reflection of quasiparticles at the core boundary. For each individual vortex the energy $\varepsilon(\mu)$ of a subgap state varies from $-\Delta_0$ to $+\Delta_0$ as one changes the angular momentum $\mu$ defined with respect to the vortex axis. At small energies $|\varepsilon|\ll\Delta_0$ the spectrum is a linear function of $\mu$: $\varepsilon(\mu)\simeq-\mu\omega$, where $\omega\approx\Delta_0/(k_F\xi)$, $\Delta_0$ is the superconducting gap value far from the vortex axis, $k_F$ is the Fermi momentum, $\xi=\hbar
v_F/\Delta_0$ is the coherence length, $v_F$ is the 